And Chloe has persistently proven since day one that she is a threat to his life and family (given every attempt at helping Teddy resulted in a disaster). And kicking her out does nothing to resolve Pandora's presence there; as she's even worse than Chloe - due to all her actions that make Teddy's life a living Hell are deliberate on her part.

So - by your definition - Teddy is a raging idiot for putting up with Chloe for that long; and continuing to allow Pandora to live under his roof.

That is a good point. Very early on in the comic, it might have made sense to keep Chloe around, as Teddy had not yet realized the extent of the threat and Chloe had no place to stay. He might, therefore, have been exercising hospitality towards a sojourner. But that excuse peters out very quickly. Chloe could have moved out as soon as she got a job as a French teacher. There isn't any reason for her to live with the Decarlos. Even if she wasn't a hazard to Teddy's live and afterlife, the possibility of Teddy's parents coming to visit and seeing a demon in their house should have been enough to get her own apartment. And Pandora? It was never explained why they let Pandora live in their house. She simply demanded to be there, and she's been there ever since.

Back then, a few silly choices could be shrugged off for the sake of comedy. Now... not so much. Too many withdrawals from that bank account.

But it's only useful advice/information if Teddy is willing to actually take it/listen to it.

Pandora made it adamantly clear that the only viable options that could survive deflowering a virgin succubus would either run in terror from Chloe (incubus) or Chloe would utterly refuse (angels). She also made it clear that mortals surviving bedding a virgin succubus were stuff of legends. Teddy, instead of listening to the reality of the situation - assumed that a jock could handle the task, despite Pandora's only comment on the idea being one of indifference, and was incredulous when Pandora told him - again - that the mortal would die. She told him all this again after a threeway romp with Al - and only then did he finally accept the reality; formulating a new plan that could easily end up killing him (much to the protest of both Al and Pandora; which Teddy - again - ignored, because he wanted to be Chloe's hero).

Other than that - Pandora has been nothing but an ever present thorn in his side; pulling pranks and making his life Hell.

She only gave him that information in chapter fourteen. That is 208 pages of her not telling him. It makes more sense that he kept her around because she resurrected his sister, but even that is after already living in his house for eighty pages. When Pandora was introduced to the comic, she impersonated Chloe, had Chloe take the fall for her crimes, and then attempted to devour Teddy. She's done some nice things since then, but that does not explain why he let her stay in the first place.